My apologies for the board's awful performance and occasional errors over the last few days. I think we've outgrown Dreamhost at this point. I'm looking into alternatives.
(And please note that there will be a bit of short-notice downtime when I go to use one of those alternatives sometime in the next few days!)
It may have been an Actual Problem rather than just the combination of accumulated posts and average-slow DreamHost. I'm trying my own PHP binary instead of theirs, and I've added a couple of database indexes in obvious sore spots.